I’ve heard it being used in several reviews and comments, most notably it’s column being removed from Crinacle’s database. I know it might generally deal with lower mids and higher bass, though I have no idea what it definitively is. I tried to find out what it is, but I couldn’t find any info other than mentions of it on several subreddits as well as Google. So what is note weight definitively, and why did Crinacle have a column for it in the first place, then neglect it and ultimately remove it?
If you want an example, think of a recording of someone playing a low piano note. On something with thicker note weight, you might hear a full-bodied “DUN!”, with emphasis being placed on the initial part of the note that makes it sound like the key is being struck more heavily. On thinner-sounding gear, you might hear a plain “DUN!” without the emphasis, making it sound like it’s being hit more weakly. Measurement-wise, it would generally be associated with the upper/lower midrange balance being skewed towards the lower mids. V-shaped/Harman IE stuff will tend to sound thinner.